Personally, I wear face paint almost everytime I fight. It helps me get into the character and into the right attitude. I have never had anyone make fun of me to my face but anytime you step out of the pack and look a little different you open yourself for ridicule. As long as you can take it in stride then go for it. Enjoy, make the game what you want it to be, and you'll have fun no matter what.
Oh, and I have never had anyone complain about paint getting onto swords.